calyptra
IPA: kʌɫˈɪptrʌ
noun
- (botany) In bryophytes, a thin, hood of tissue that forms from the archegonium and covers the developing sporophyte and is shed as it ripens.
- (botany) any cap-like covering of a flower or fruit, such as the operculum over the unopened buds of Eucalyptus flowers
- (botany) Any of various coverings at the tips of structures, in the terminology of various authors; for example rootcaps and the apical cells of trichomes.
- (entomology) In flies such as the housefly, Musca, in the taxonomic order Diptera, zoological section Schizophora, subsection Calyptrata, the calyptra is a membranous rearward extension of the forewing; it covers the haltere.
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Examples of "calyptra" in Sentences
- _D_, capsules of _Bartramia_: i, with; ii, without the calyptra.
- The sporogonium when nearly mature bursts the calyptra irregularly.
- _C_, young capsule of hairy-cap moss (_Polytrichum_), covered by the large, hairy calyptra.
- The young sporogonium is protected by a thick calyptra derived from the tissue of the thallus around the archegonium.
- It remains for long enclosed within the calyptra formed by the further development of the archegonial wall and surmounted by the neck of the archegonium.
- The upper portion of the archegonial wall is carried up as a calyptra on the sporogonium, which, as in _Sphagnum_, has no seta and is raised on a pseudopodium.
- The terminal cell is always solitary, very often attached to the one next it, which is generally single, obliquely placed, occasionally looking like the dimidiate calyptra capping a young seta.
- _ Longitudinal section of the summit of a shoot bearing a nearly mature sporogonium, sg, still enclosed in the calyptra; ar ', archegonia which have remained unfertilized; st, stem; b, leaf; p, perianth.
- The spore-bearing generation consists of a long stalk, closely held below by the cells of the base of the archegonium; this supports a broadened portion which contains the spores, and the top is covered with the remains of the neck of the archegonium forming the calyptra.
- A case in which the future organs of reproduction are developed; and here is a most curious circumstance, namely, that though the calyptra, which is a genuine pistillum containing an _ovulum_, becomes torn up from its base, yet it remains in contact with that part of the seta in which the sporules are developed until these make their appearance, or even later!! so that one might as well deny a pistillum to a Reseda, or Leontice, as deny it to these plants on the strength of its being torn from its attachments.
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